1. Field of the Invention
The present invention relates to a multilayer ceramic capacitor, and more particularly, to a multilayer ceramic capacitor that may uniformly harden conductive resin by hardening the conductive resin through an irradiation cross-linking method using gamma ray.
2. Description of the Related Art
A multilayer ceramic capacitor includes a ceramic plastic body formed so that a plurality of internal electrode layers may be alternately disposed, and an external electrode formed in each of both ends of the ceramic plastic body and including a plurality of conductive layers. The multilayer ceramic capacitor is mounted to a printed circuit board using a surface mounting method. Due to the above mounting structure, when an external force is applied or when the printed circuit board is bent, stress may be transferred to the multilayer ceramic capacitor by the external force or bending through a soldering portion.
When the stress is applied to the multilayer ceramic capacitor, the ceramic plastic body and the external electrode may be separate from each other due to the stress or crevice may occur in the ceramic plastic body. Accordingly, a short phenomenon that the internal electrode layers are electrically connected to each other may occur. As technology for preventing the above short phenomenon, technology of forming a conductive body (hereinafter, referred to as conductive resin) including resin as a buffering material on a conductive layer connected to the plurality of internal electrode layers among the plurality of conductive layers is being developed.
In the case of the conventional multilayer ceramic capacitor, thermosetting resin is included in conductive resin. The thermosetting resin is hardened through heat treatment in a temperature of 150 degrees to 300 degrees for 10 hours to 24 hours and thereby is prepared. The conductive resin acts as a buffering material to absorb the stress that is applied to the multilayer ceramic capacitor and thereby decrease the stress against the external electrode. Accordingly, the conductive resin may prevent the occurrence of the short phenomenon that the ceramic plastic body and the external electrode are separate from each other due to the stress or crevice occurs in the ceramic plastic body whereby the internal electrode layers are electrically connected to each other.
As described above, conductive resin used for the external electrode of the conventional multilayer ceramic capacitor is hardened using a thermosetting method. Accordingly, when heat is unevenly transferred to the conductive resin during a hardening process, an insulating film is formed on an interface of the conductive resin to thereby degrade an electrical characteristic of the multilayer ceramic capacitor. Also, in the case of the conventional conductive resin, foreign substance may occur as a by-product during a thermosetting process. When the foreign substance is adhered to the external electrode, fault may occur in the appearance of the external electrode, thereby degrading the productivity of the multilayer ceramic capacitor.